Cytomorphology of pleomorphic fibroma of skin: A diagnostic enigma

Abstract

Pleomorphic fibroma (PF) is a benign, polypoid, or dome-shaped cutaneous neoplasm with cytologically atypical fibrohistiocytic cells. We describe the cytomorphological features of PF retrospectively with histopathological diagnosis in a 38-year-old male who presented with 3 × 1.5 cm swelling in the soft tissues of the thigh for 6 months. This lesion is benign despite the presence of pleomorphic or bizarre cells. We review the differential diagnosis of PF with other mesenchymal tumors. To the best of our knowledge, cytomorphological features on fine needle aspiration cytology of this tumor are not yet documented in literature.

Pleomorphic Fibroma Presenting as a Nodular Lesion in the Left Shoulder: A Case Report

“…PF is a rare benign fibrous neoplasm that typically manifests as a single asymptomatic lesion characterized by cellular atypia and pleomorphism without mitosis [ 3 ]. Similar atypia is seen in tumor cells of fibrohistiocytic skin tumors such as AFX, pleomorphic dermal sarcoma, and undifferentiated pleomorphic sarcoma.…”

“…The tumor often develops in adults and has a slight sex bias in favor of women [ 2 ]. This type of fibroma prefers the lower extremities, followed by the trunk, head, and neck, and is less frequently observed in the subungual region [ 3 ]. PF manifests as asymptomatic, solitary, skin-colored, dome-shaped, or polypoid papules that range in size from a few millimeters to almost 2 cm in diameter.…”

A solitary polypoid papulonodule on the knee of a 13‐year‐old girl

“…Histopathology is characterized by a dermal tumor with scattered spindle cells and pleomorphic multinucleated cells but low cellularity and lack of mitotic figures, in contrast to malignant lesions. 5,6 Some multinucleated cells may have multilobed or hyperchromatic nuclei. 5 Positive expression of vimentin, CD34, muscle-specific actin, and factor XIIIa has been observed.…”

“…5 Positive expression of vimentin, CD34, muscle-specific actin, and factor XIIIa has been observed. 5,6 Immunohistochemistry is typically negative for S-100, CD68, desmin, and cytokeratins. 5,6 The histopathologic differential diagnosis for PF includes dermatofibroma with monster cells, giant cell fibroblastoma, pleomorphic lipoma, atypical fibroxanthoma, desmoplastic Spitz nevus, and desmoplastic melanoma.…”

“…5,6 Immunohistochemistry is typically negative for S-100, CD68, desmin, and cytokeratins. 5,6 The histopathologic differential diagnosis for PF includes dermatofibroma with monster cells, giant cell fibroblastoma, pleomorphic lipoma, atypical fibroxanthoma, desmoplastic Spitz nevus, and desmoplastic melanoma. 5,6 Dermatofibroma with monster cells may similarly demonstrate large atypical cells with hyperchromatic nuclei on histology; however, hemosiderin laden macrophages with negative expression of CD34 differentiate this entity from PF.…”